In many surgical procedures, it is desirable to provide one or more working channels into a body cavity through which various instruments can be passed to view, engage, and/or treat tissue to achieve a diagnostic or therapeutic effect. In laparoscopic abdominal procedures for example, the abdominal cavity is generally insufflated with CO2 gas to a pressure of around 15 mm Hg. The abdominal wall is pierced and one or more tubular cannulas, each defining a working channel, are inserted into the abdominal cavity. A laparoscopic telescope connected to an operating room monitor can be used to visualize the operative field and can be placed through one of the working channels. Other laparoscopic instruments such as graspers, dissectors, scissors, retractors, etc. can also be placed through one or more of the working channels to facilitate various manipulations by the surgeon and/or surgical assistant(s).
One problem with existing methods and devices is that the thickness of abdominal tissue which must be traversed by the cannula varies from patient to patient. As a result, when working with fixed length devices, a variety of different length cannulas are required to be on hand and the surgeon must estimate the thickness of the abdominal tissue for the particular patient and then select a cannula having the proper length. This process is cumbersome and can result in the insertion of cannulas that have an excess length within the patient. When cannulas are placed in close proximity to each other, such excess cannula length can cause interference between working channels and the instruments passed therethrough. The excess length can potentially cause damage to patient tissue if the excess length is significant.
Another drawback to existing access devices is that they do not retract tissue beyond the initial incision to any appreciable degree. Instead, they generally have a rigid body with a straight tubular shape that dramatically limits the range of angles at which surgical instruments can be positioned when passed therethrough. Angulation of such instruments thus requires angulation of the entire access device, which can cause these existing devices to suffer from decreased retention and stability and from poor seal integrity between the access device and adjacent tissue. Sutures, stability threads, deployment anchor mechanisms, and collars have been developed in an attempt to address these concerns, however further improvements would be desirable, particularly for smaller-diameter access devices or where extreme angulation is required.
Accordingly, there is a need for surgical access methods and devices that provide optimal device length and improved tissue retraction, tissue wall retention, stability, and seal integrity.